The invention relates to a spiral heat exchanger. More particularly, it relates to a restorative or recuperative spiral heat exchanger with spirally extending separating walls between streams of fluid medium having an exploitable temperature gradient. It especially relates to such a heat exchanger wherein each two adjacent separating walls enclose between themselves a flow duct for one of the two streams of medium, and the spiral space disposed between two flow ducts forms the path of flow for the other stream of medium.
Spiral heat exchangers are known, and such heat exchangers with spirally arranged flow ducts may be advantageously operated by the countercurrent or counterflow heat exchange principle, which permits large areas of heat exchange surface in a small space. However, a spiral heat exchanger has the drawback that the flow paths are relatively long because they are disposed in a spiral, which leads to high pressure losses. Furthermore, extensive flow paths make it more difficult to securely seal the heat exchanger. The cleaning of such heat exchangers also poses problems, and their operation with higher pressure differences requires an above-average expenditure in terms of engineering and constructions. These drawbacks are the reasons why spiral heat exchangers, until now, have failed to find wide acceptance in the market.
Accordingly, it is an object of the invention to provide a spiral heat exchanger wherein the above-identified drawbacks are eliminated.